Self-cleaning centrifugal separator



July 23, 1968 M. BARAM 3 SELFCLEANING CENTRIFUGAL SEPARATOR Filed Aug.9; 1966 & 3

v f I 1 z I l I 16 \42 45 mvewron By Men/v EAR/1M ATTORNEY United StatesPatent 3,393,863 SELF-CLEANING CENTRIFUGAL SEPARATOR Martin Baram,Svanliolmvej 13, Vallensbaek pr., Brondby Strand, Denmark Filed Aug. 9,1966, Ser. No. 571,211 Claims. (Cl. 233-20) ABSTRACT OF THE DISCLOSURESelf-cleaning centrifugal separator having an upper portion and a lowerportion divided by a peripheral ejection slit that is opened and closedby fluid operated means.

The invention concerns a self-cleaning centrifugal separator,particularly for laboratory work, which consists of an upper and a lowerpart divided by a peripheral ejection slit that can be opened and closedby a hydraulically or pneumatically controlled device.

Existing self-cleaning centrifugal separators that are now utilized forindustrial and production purposes employ hydraulic or spring drivenmeta-l piston shut-off devices that are cumbersome and are not readilyadaptable for use with small and high speed rotating centrifuges thatare employed for analytical, research, and laboratory purposes. Where ithas been suggested that elastic membranes of various shapes may beutilized as shut-off devices for centrifuges, such membranes have neverproven to be practicable because the membrane means that are known inthe art display various functional drawbacks such as lack ofcontrolability and inadequate wearing qualities. Also, such prior artmembranes are not readily replaceable because of the complex structureof the centrifuge. Furthermore, in most cases it has not been possibleto ensure satisfactory emptying of the centrifuge because sludge andother similar dirt clog the separate spaced openings in the perpihery ofthe centrifuge.

An object of the invention is to overcome the disadvantages of prior artself-cleaning devices and to provide a self-cleaning centrifugalseparator that is particularly useful for laboratory work but notexclusively limited thereto.

Another object of the invention is to provide a simple centrifuge whichincludes a hydraulically or pneumatically controlled opening and closingdevice cooperating with an unbroken peripheral ejection slit.

A further object of the invention is to provide a centrifugal separatorwith exchangeable parts to adapt the centrifuge to varying purposes.

A still further object of the invention is to provide a centrifugalseparator with exchangeable parts that permit a quick and easyreplacement of worn parts.

Another vital object of the invention is to provide a centrifugalseparator which is furnished with a fluid controlled mernbrane-likeshut-ofl device which by virtue of its shape and position closes theejection slit securely, opens the ejection slit satisfactorily, andhelps to prevent clogging of the ejection slit.

The invention shall be explained in more detail in connection with theattached schematic drawing which shows an embodiment of the invention byway of an example which does not limit the invention to its secondarydetails.

The centrifuge consists of a circular upper part 1 and a circular lowerpart 2, the latter comprising an outer vessel 3 and an inner vessel 4between which is defined a circular space 5. A pipe 6 which is coaxial-with the rotation axis is at its lower end in open communication withspace 5 through channels 16 which also indicate that pipe6 is screwedonto part 2, thus, channels 16 are segmental openings in a thread. Pipe6 has at its upper end a flange 14 3,393,863 Patented July 23, 1968 icewhich helps to contain any fluid control medium. Space 5 is limited atthe upper edges of vessels 4 and 3 by an annular support ring 9 whichhas one or more spaced apart borings 8 to admit a control fluid mediumto an annular space under an elastic membrane 10, said support ring 9also being furnished with one or more spaced apart borings 11 to letsome of the control fluid escape constantly. The peripheral portion ofmembrane 10 is held in place by a ring 13 secured by screws 16 which arepressed down by screws 15 which connect the upper part 1 with the lowerpart 2 by means of the support ring 9. Screws 16 determine the height ofan ejection slit 12. The membrane 10 is held in place on the axial sideby the upper edge of inner vessel 4 which at its lower circular edge ispressed down by said pipe 6 in such a manner that no control fluid canmake its way from pipe 6 into the inner vessel 4.

The drawing shows clearly the most important features of the inventionwhereby that it provides a simple construction, the various parts ofwhich can be exchanged or replaced with ease. Thus, by removing a numberof screws 15 the upper part 1, the ring 13 wit-h spacing screws 16, areeased upwardly and half the membrane 10 is thereby loosened, the otherhalf of membrane 10 being relieved by loosening pipe 6, which whenentirely removed also releases inner vessel 4. The inner vessel 4 canhave various shapes in accordance with the work to be done by thecentrifuge, and the same criteria apply to the choice of material whichcan be stainless steel sheets or other chemically suitable material.Also, membrane 10 can easily be replaced either because it is worn orbecause different purposes demand different characteristics. Themembrane can be of rubber or any suitable plastic material or of acombination of materials. When upper part 1 is removed, the height ofslit 12 can be changed by adjusting screws 16. The upper part 1 made ofa transparent material such as Plexiglas to observe and control thecentrifugation, and it is furnished with an opening 7 through which thecentrifugating material can be entered and/ or taken out at will whilethe centrifuge is rotating.

The centrifuge works in the following manner:

When rotating by means of elements A, fastened to any conventionaldriving device, a suitable operating medium such as Water is sentthrough flange 14, pipe 6, channels 16, space 5 and borings 8 to arrivein the annular chamber defined by the under side of membrane 10, andthus a hydrostatic pressure is cen-trifugally generated which forcesmembrane 10 to expand and to seal ejection slit 12 against upepr part 1.As long as the supply of control fluid compensates for the lossesthrough boring 11, the membrane 10 will be urged tightly against upperpart 1, and thus any contents of inner vessel 4 will be held inside therotating body of the centrifuge. When observation through upper part 1or other means indicate that the contents in vessel 4 are to be ejected,the supply of controlling fluid in space 5 is either slowed down orstopped. In the first instance of slowing down the controlling fluid,the centrifugated material in vessel 4 will leave very slowly throughslit 12 making it possible to stop the ejection at any point by renewingfull fluid pressure in space 5, in the other instance of stopping thecontrolling fluid, the ejection will be sudden and thorough leaving theinner vessel 4 absolutely clean and ready to receive the next batch. Allthese operations, i.e. filling the inner vessel 4 and emptying it boththrough opening 7 and ejection slit 12 are practiced while thecentrifuge rotates at full speed, and theoretically the centrifuge doesnot need to be stopped as long as there is work for it to do.

As shown in the drawing, membrane 10 is under fluid pressure to touchpart 1; but it is obvious that without fluid pressure in space 5membrance 10 will be recede away from part 1, and uncover ejection slit12. Not so obvious is the special feature that the stretching andrelaxation of the flexible membrane 10 helps to loosen any obstinatecentrifug-ated material which otherwise would resist ejection. Thisfeature is furher enhanced by the fact that the centrifugated materialcollects inside an unbroken peripheral slit 12.

Experience has shown that the centrifugal separator according to theinvention can be made in quite small dimension, e.g. a maximum diameterof 100 mm. at its widest diameter, and it works perfectly at speedsabove 10,000 r.p.m.; thus, a new and hitherto unknown tool forlaboratory work has been provided. Obviously, the principles of theinvention can also be applied to industrial centrifuges of largedimensions.

What is claimed is:

1. Self-cleaning centrifugal separator, particularly for laboratorywork, which comprises an upper and a lower part divided by a peripheralejection slit that can be opened and closed by fluid operated means,said lower part consisting of an inner vessel and an outer relativelyspaced and detachable vessel, the outer vessel being furnished withfastening means to engage a driving device, a pipe for the supply of afluid control medium, said pipe extending coaxially with the axis ofrotation through an opening in the upper part and being in fluidconveying communication with the space between said inner and outervessel, said space at its peripheral end being in fluid conveyingcommunication with an annular elastic shut-off device which in acontrollable manner according to fluid pressure in said spacealternatively seals and uncovers said peripheral ejection slit betweensaid upper and lower part.

2. Centrifugal separator as in claim 1 wherein the inner vessel has theshape of an outwardly slanting cup.

3. Centrifuge as in claim 1, wherein the inner vessel has the shape ofan almost horizontally extending dish.

4. Centrifuge as in claim 1 wherein the upper part consists of a flattransparent disc.

5. Centrifuge as in claim 1, wherein the annular elastic shut-off deviceconsists of a membrane positioned inside an annular element whichdefines one side of the ejection slit and keeps said space between theinner and the outer vessel in fluid conveying communication with thespace under the membrane in such a manner that the membrane when notunder the influence of the fluid control medium uncovers the ejectionslit and while when under the suflicient pressure of said medium expandssaid membrane which seals said ejection slit.

References Cited UNITED STATES PATENTS 3,281,068 10/1966 Baram 233--20HENRY T. KLINKSIEK, Primary Examiner.

